Scientific Forecaster Discussion

Aviation... for the 18z tafs...deteriorating weather is expected at all terminal sites during this forecast cycle. A strong cold front will move across the taf sites later this afternoon and evening...with much colder air invading the region tonight and Wednesday. In addition...a fast moving upper level storm system will track through the southern High Plains later tonight and Wednesday...and will bring a mixed bag of precipitation...starting off as -ra...then transitioning to -fzra or -rasn...and finally all snow. Ceilings will gradually lower to IFR and visibilities will drop accordingly as well due to precipitation and br.

Andrade

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Previous discussion... /issued 541 am CST Tuesday Mar 3 2015/

Aviation... 12z taf cycle VFR conditions to start the taf forecast package this morning with only some patchy fog which expected to dissipate by 15z today. A cold front will push across the three taf sites this evening around 23z today to 03z Wednesday resulting in easterly to northeast winds 10 to 20 knots after the passage of the cold front. Ahead of the front this morning through this afternoon...southwest to west winds 10 to 20 knots expected. An upper trough will approach the taf sites tonight and Wednesday which will cause the VFR conditions to become MVFR around 21z to 23z today...and then become IFR to vlifr after 01z to 03z Wednesday. Light rain by 01z Wednesday will become mixed with and then change over to snow by 06z Wednesday and continue through 12z Wednesday.

Schneider

Previous discussion... /issued 430 am CST Tuesday Mar 3 2015/

Short term...today and tonight

Early morning water vapor satellite imagery indicates a deep upper low near Baja California California with southwest upper flow over the Southern Plains. Despite breezy southwest winds overnight...areas of fog have persisted early this morning. Expect the fog to erode later this morning as drier air moves into the area on southwest low-level flow. Still expect to see considerable cloudiness today but also expect a nice warm up for today with highs in the 50s to near 60 degrees in the southern Texas Panhandle.

This warm up will be brief...however...as an Arctic front plunges into the area later this afternoon/evening. Model guidance are in good agreement in developing light wintry precipitation in the wake of this front...as forcing for ascent increases. Since temperatures will start out well above freezing...precipitation type will start out as rain particularly over the southern Texas Panhandle where the front is not expected to push through until later this evening. However strong cold air advection will quickly cause precipitation phase to transition to snow across the Oklahoma Panhandle and the northern half of the Texas Panhandle. However complicating the forecast is the possibility for light freezing rain and/or drizzle as model soundings indicate dry air in the snow growth zone this evening/tonight. Decided to go with a rain/snow mix over the northern zones. However will have to continue to keep a close eye on this. The passage of this cold front will lead to a cold night...with lows in the teens to lower 20s.

Long term...Wednesday through Monday snow event should be unfolding across the area Wednesday with the upper low opening up over The Four Corners region. There may be a small window of freezing rain/drizzle over the southern Texas Panhandle early Wednesday morning...but the column will quickly saturate indicating snow will be the main precipitation type during the remainder of the event. Qg forcing and isentropic ascent has raised confidence in a period of light snow especially in the afternoon when the upper lift will be maximized. Of lower confidence will be snowfall accumulations as this system is fairly progressive which should limit total snowfall. Went with a general 1 to 2 inches...which fits in a potential Winter Weather Advisory. However opted to not issue a Winter Weather Advisory with this package as snowfall accumulations can be lower depending on if and how long rain/freezing rain/freezing drizzle will precede the snowfall.

Any precipitation will shift off to the southeast Wednesday night as isentropic downglide develops over the area. Skies will also quickly clear Thursday morning. Downsloping southwest winds and mainly clear skies will result in a noticeable warm up Thursday where high temperatures will climb into the 40s as opposed to the 20s Wednesday. Even warmer temperatures along with dry conditions are expected late this week through early next week as an upper ridge amplifies over the western Continental U.S.. several upper-level disturbances dropping southeastward in the northwest upper flow can push a couple of weak cold fronts through the area Friday and Sunday...although these will have little impact on the sensible weather across the area. Overall expect high temperatures in the 50s to low 60s through this period.